The following generally relates to industrial plant process automation optimization and is described with particular application to a mineral plant; however, the following is also amenable to other industrial plants.
Mining, generally, is the extraction of a material from the earth. Examples of materials that are mined from the earth include, but are not limited to, metal such as copper, iron, uranium, coal, diamonds, limestone, oil shale, rock salt, potash, petroleum, natural gas, water, and/or other material. Such materials may be contained in an orebody, lode, vein, seam or reef, which forms the mineralized horizon. Copper mining will be discussed next in more detail as an example of a mining process.
Copper mining includes extracting copper ore from the earth and then extracting the copper from the ore. This conversion consists of a series of chemical, physical, and electrochemical processes. For example, the ore is first crushed. Then it is roasted to convert sulfides to oxides, which are smelted to produce matte. Finally, it undergoes various refining processes, the final one being electrolysis. For economic and environmental reasons, many of the byproducts of extraction are reclaimed.
More specifically, copper ores are often obtained from large open-pit mines by drilling and blasting with explosives. The material located above the ore is first removed to expose the buried ore deposit. The copper ore is removed and loaded into a transportation vehicle, called a haul truck, and is transported up and out of the pit. The copper typically contains a large amount of dirt, clay, and a variety of non-copper bearing minerals.
From the literature, the first step to extracting the copper is to remove some of the non-copper material. Examples of approaches for doing so include, but at not limited to, crushing the copper ore with a series of cone crushers, which consists of an interior grinding cone that rotates on an eccentric vertical axis inside a fixed outer cone. As the ore is fed into the top of the crusher, it is squeezed between the two cones and broken into smaller pieces.
The crushed ore is then ground even smaller by a series of mills. First, it is mixed with water and placed in a rod mill, which consists of a large cylindrical container filled with numerous short lengths of steel rod. As the cylinder rotates on its horizontal axis, the steel rods tumble and break up the ore into smaller pieces. The mixture of ore and water is further broken up in two ball mills. The slurry of finely ground ore that emerges from the final ball mill contains particles about 0.01 in (0.25 mm) in diameter.
The slurry is mixed with various chemical reagents, which coat the copper particles. A frother (e.g., pine oil or long-chain alcohol) are added, and the mixture is pumped into rectangular tanks where air is injected into the slurry through the bottom of the tanks. The chemical reagents make the copper particles cling to the bubbles as they rise to the surface. The frother forms a thick layer of bubbles, which overflows the tanks and is collected in troughs. The bubbles are allowed to condense and the water is drained
The copper concentrate is fed into an oxygen-enriched flash furnace along with a silica material flux. Iron chemically combines with the flux to form a slag and is skimmed off, and sulfur combines with the oxygen and is exhausted. Generally, this process is repeated and the resulting molten material contains a higher concentration of copper by weight. The molten material is then refined and cast into ingots, cakes, billets, or rods depending on the final application.
However, the mining process is confronted with various challenges. Such challenges include maximizing output, which includes ending up with a predetermined threshold concentration of copper in the refined final product considering the initial ore may include less than 1.0% of the material of interest. Other challenges include mitigating environmental, health and/or safety concerns, minimizing down time, reducing energy cost, optimizing allocation of recourses, getting properly trained individuals to remotely located mines, etc. Thus, there is an unresolved need for improving the mining process.